Behavior of axially loaded steel short columns subjected to a localized fire

Zhang, Chao; Choe, Lisa; Seif, Mina; Zhang, Zhe

doi:10.1016/j.jcsr.2014.11.012

Cited by 21 publications

(5 citation statements)

References 24 publications

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“…The numerical results from 900 finite-element models were used to develop a closed-form equation that predicts critical temperatures of steel columns as a function of member slenderness and load ratio. The three-dimensional linear polynomial model, as shown in Figure 3, was employed scaled value was taken as the larger of a web out-of-flatness equal to the ratio of the section depth over 150 (Kim and Lee, 2002) or a tilt in the compression flanges taken as the ratio of the flange width over 150 (Zhang et al, 2015). No residual stresses were applied because their influence is limited at elevated temperature (Vila Real et al, 2007).…”

Section: Proposed Closed-form Equation Compression Membersmentioning

confidence: 99%

Critical Temperature of Axially Loaded Steel Members with Wide-Flange Shapes Exposed to Fire

Sauca,

Chicchi,

Zhang

et al. 2021

Eng J

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This paper presents closed-form equations that were developed to evaluate critical temperatures of structural steel compression and tension members exposed to fire. The deterministic approach involved a parametric study using finite element simulations in order to identify influencing factors—for example, mechanical properties of steel, member slenderness, and axial load ratios. Statistical models were employed to develop closed-form equations representing the best fit of numerical results. A comparison with experimental column test data indicates that the proposed equation for compression members provides a conservative lower bound (16% lower on average) relative to the test data at load ratios greater than 0.3. A sensitivity study was also performed to further explore uncertainty in predicted critical temperatures due to variability of axial load ratios. For both compression and tension members, the ambient-temperature yield stress of steel, Fy, has a great impact on determination of axial load ratios, subsequently influencing the overall accuracy of the critical temperature estimated by the proposed equations. The applicability of the proposed equations is limited to wide-flange steel members that are simply supported, concentrically loaded, and exposed to uniform heating.

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Section: Proposed Closed-form Equation Compression Membersmentioning

confidence: 99%

Critical Temperature of Axially Loaded Steel Members with Wide-Flange Shapes Exposed to Fire

Sauca,

Chicchi,

Zhang

et al. 2021

Eng J

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“…Since the (average) hot gas temperature calculated by the two zone model is not high, it is usually thought that pre-flashover fires are not hazardous to structures. However, the local high temperature in a pre-flashover fire (as shown for the case with a low ceiling in Fig 19) can indeed damage structural components near the fire source especially when there is flame impingement, as found in [19, 20, 21, 22, 23]. Therefore, a localized fire model instead of a two zone model is recommended for structural fire design.…”

Section: Thermal Calculation In a Pre-flashover Fire Environmentmentioning

confidence: 99%

Heat transfer principles in thermal calculation of structures in fire

Zhang

Usmani

2015

Fire Safety Journal

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Structural fire engineering (SFE) is a relatively new interdisciplinary subject, which requires a comprehensive knowledge of heat transfer, fire dynamics and structural analysis. It is predominantly the community of structural engineers who currently carry out most of the structural fire engineering research and design work. The structural engineering curriculum in universities and colleges do not usually include courses in heat transfer and fire dynamics. In some institutions of higher education, there are graduate courses for fire resistant design which focus on the design approaches in codes. As a result, structural engineers who are responsible for structural fire safety and are competent to do their jobs by following the rules specified in prescriptive codes may find it difficult to move toward performance-based fire safety design which requires a deep understanding of both fire and heat. Fire safety engineers, on the other hand, are usually focused on fire development and smoke control, and may not be familiar with the heat transfer principles used in structural fire analysis, or structural failure analysis. This paper discusses the fundamental heat transfer principles in thermal calculation of structures in fire, which might serve as an educational guide for students, engineers and researchers. Insights on problems which are commonly ignored in performance based fire safety design are also presented.

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“…These studies suggest that structural members subjected to thermal gradients behave fundamentally different from how they were originally conceived, leading to the potential of a premature failure. In addition, another study by Zhang et al found that the failure temperature of steel columns subjected to an adjacent localized fire could be higher or lower than the failure temperature predicted by the standard fire curve. These studies show that the current design codes do not have the capability to predict the behavior of structural elements subjected to localized heating, and therefore, a more detailed approach to modeling these structures is needed.…”

Section: Introductionmentioning

confidence: 99%

Best practices for modeling structural boundary conditions due to a localized fire

DeSimone

Jeffers

2019

Fire and Materials

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Summary Recent studies suggest the assumption of uniform heating that is used in current structural fire design cannot be assumed conservative, especially if the fire is expected to burn locally. Aside from design equations, which have limited applicability, a common approach to simulating structural members subjected to a localized fire is modeling the fire‐structure interaction using a coupled computational fluid dynamics (CFD)‐finite element (FE) model. In the existing literature, a wide range of methods and parameters are used when determining the boundary conditions at the fire‐structure interface, specifically regarding the representation of net heat flux, heat transfer coefficient, and surface emissivity of steel. The purpose of this study is to investigate various methods for representing the boundary conditions in terms of accuracy and computational efficiency and then identify best practices. In conclusion, our study found that net heat flux predicted by adiabatic surface temperature, a nonconstant heat transfer coefficient, and a surface emissivity of 0.9 for steel was the most reliable thermal boundary condition in a coupled CFD‐FE model of a localized fire. These recommendations are based on the two cases studied here, and caution should be used when applying these results to future studies.

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Behavior of axially loaded steel short columns subjected to a localized fire

Cited by 21 publications

References 24 publications

Critical Temperature of Axially Loaded Steel Members with Wide-Flange Shapes Exposed to Fire

Critical Temperature of Axially Loaded Steel Members with Wide-Flange Shapes Exposed to Fire

Heat transfer principles in thermal calculation of structures in fire

Best practices for modeling structural boundary conditions due to a localized fire

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